Heating Water for Pool

Billdad, did you mean natural circulation?

I'm not sure of the proper name but natural circulation sounds better.

Well, I did some research and it is natural convection. In this case I am talking about a thermosypon.

Thanks for the comment,

Bill

a.k.a. natural convective heat transfer or free convection...

Hi ,

Some of the criteria u should consider prior to the heating system of pool .

1. Average ambient temperature of your region. u can get it from ASHRAE.ORG.

2. Pool size , Indoor/Outdoor.

3. Normally the evaporation loss is 70 % . Radiation losses -20 % and ground losses -10 %.

4. Heating hours required for pool heating shall be determined based on the Absorption of Heat energy from sun .

5. It only takes 1 Btu (British thermal unit) to raise 1 pound of water 1 degree, but each pound of 80ºF water that evaporates takes a whopping 1,048 Btu of heat out of the pool.

6. Instead of going for a high investment in Gas heaters or pumping system . Go for a bubble cover with Insulating effect . The bubble cover will help you to gain 3- 5 deg c with its insulating effect not allowing the water to evaporate .- Source - Daisy Pool Covers.

7. If there is a scare of Solar energy in your area then you can opt for a Gas heaters with dual system (Either Naptha or Natural Gas Firing)- in addition to pool covers.- Source - Raypack Hi Delta Heaters.

8 . Using of pool covers will also help you to conserve water y reducing the amount of makeup water needed by 30-50%.

9. Reducing the pool chemical consumption by 35-60%.

Hi shahand,

A friend had a swimming pool about the size of a Tennis Court. This was in the UK.

He had all the various filtration pumps in a purpose built building. He and I then bought so flat type heating radiators. There was 6 4' x 6' radiators and we built a solar panel long enough for these radiator, with the whole thins facing South.

He then had ½ pipe which joined all the rad' together, and then a pipe from the now fixed array of these solar panels down one side of his pool to a filter from the pool pump, and although the average temp was little more than perhaps 60 °F, it was enough to heat the pool to a comfortable level.

The man whose garden this was fitted was a fully qualified Engineer and there was no 'guessing', all was worked out before the rads were bought and enclosed in Plexiglas with all the inside and the radiators painted a Matt black. He never had to run the main filter pump any longer than he already did without the solar panels connected, so it cost no 'extra' money other than the price of the radiators and Plexiglas and frames. We fitted a normal sized central heating pump and this was left as a back-up, but was not used after the first month which it took to heat the water, obviously, with the arrangement we had the water very gradually got warmer day by day and in addition he also built a pool cover which was left in place, and helped the heating process a lot.

I know it works so why not give it a try?

Take care.

Hi all, I made an error in my post 39.

It should have said "1" pipe.

NOT ½".

bb

You can call it FM* or natural convection or inverted free convection or just plain old convection but the pool got warm eh?

* Funky Magic!

Why go high tech when low tech works.

60 feet of 2inch black ABS pip with requesite elbows and an adapter to a normal garden hose or other suitable water supply.

Take the ABS and place it somewhere where it gets sun for a large part of the day. plumb it so that Hose from your water supply is at one end and the hose from the other end is close enough to your pool to dump the hot water into.

The above system is in use at my parents in ground pool (16 feet X 32Feet with a shallow end on the side of 16feet X 15 feet Deepest section is 9 feet). The ABS heats up 60 feet of water every 2 hours from over night temp to hot with no trouble. every few hours on an average sunny day we crack open the ball valve and let a small trickle out and run this for about 30 minutes or until the water is not warm to the touch. Then close and wait. The tube is placed on concrete patio stone on the east side of the yard at the feet of a flower bed. The source water is the outside tap with another ball valve permanently set to a very slight opening.

The temperature of this in ground pool can be raised by 10 degrees every week of MODERATE sunshine for Ottawa Canada. If your in some place like Arizona you could probablly get the same results in a day or two.

If you want to pump the water around and avoid manual labour get a small solar panel for 12v battery charging and a fish tank pump. house the pump and inverter inside a weather proof enclosure and mount the panel on top. when the sun shines the little pump will send enough water through the 60 feet of 2" ABS pipe that it will warm your small above ground pool daily. If you want to heat day and night add a 12v battery and a fish tank heater, and a light sensor and your off to the races.

With the various bits you have you should be able to cobble together a decent passive solar pool heater that costs almost nothing to build. A good location to place your tubing may be around the hand rail for the deck around you above ground pool.

To pump you could use a light coloured intake pipe draped into the bottom of the pool and the rest of teh pipe is DARK (black). when it heats it should expand and start a natural pump action providing warm water out near the surface while drawing cold water in from the bottom to reheat.

See Post #17, not dissimilar to yours really, but no need for a long black pipe and it has been working for more than 30 years to my knowledge.....old and still wiley engineer of the old school made it!! Not me, but I would copy it if I ever got a pool at home INSTANTLY!!

The last time I saw it he had a pump running from some solar cells ( a couple of big panels he had left over from a customer job!!) that ran when it was sunny.....

Black plastic tube does not transmit heat as well as steel roofing, painted black I feel...

But each to his own!!

Yes the steel roof would work better but as he has some odds and ends around he is most likely to have ABS tubing or some similar material. The ABS also works very well on teh roof using the outdoor tap as the force to raise the water to the roof line. The standard roofing shingles reduce heating time by 2 days for the pool I used. It also is a good way to clean the deck around the pool or to mix the powedered chlorine for the pool as it dissolves the powder faster, works pretty good on Chlorine pucks as well.

Kaboom, thanks I've thougth about some ways like that (only more $$$), but ABS pipe, I like it! Doug

I'd have thought direct radiation from the sun was much more effective than trying to use hot air.
There have been several threads and blogs on this topic.
Big bore black pipe does quite well and you could always scale up the sort of thing I did in my DIY solar panels. (Click on my user name and you'll find a link on the my user page).
Convection/thermosyphon/whatever you want to call it, is a very weak force and unreliable.
As someone already pointed out, you have a pool pump running alread, just route some of the water through solar collectors.
As already pointed out, try to minimise heat loss at night.
Del

Minimizing heat loss over night is no trouble they sell a thing called a solar blanket for pools ... okay its blue bubble wrap. keeps a good portion of the heat in overnight, great fun to try and run across a pool on, hard on the blanket though; but it works.

Most pool pumps are sized for moving the water with a bit extra room for when the filter is clogged. IF your pump is at one of the standard sizes, whatever they are, then you wont have a lot of extra room to play with. If it is at the bottom end of the pumps usefull work area then your laughing. but again why go to all the trouble of paying for a heating panel when you already have the tubes and most of the fittings already for a passive solar heater that can be placed around the pool ? Cost of the ball valves for a garden hose is what a few bucks ? You could even set up a watering line that runs around the backyard to all the flower beds. This will let you open the valve to water the plants and you dont have to run around with a hose on those hot days. the spray nozzles and tubbing for this are not too expensive and work pretty good, again did this at the parents place so they dont have to walk around the yard too much since they are getting older. 3 Y adapter ball valves 300' of black 1/2" tubing 20' of 1/4" tubing, 60 spray nozzles and a few sections of old garden hose with new ends attached. Add to this the passive pool heater and you end up with about 10 minutes of good hot water, at full open, to heat the pool every few hours.

Sure a heater on the roof is better, but everytime you replace the shingles up there you have to tear down the heater to do it and then rebuild the heater. If the heater is around the pool you build it once and leave it.

As for pool heating from direct sunlight, its more about the volume to heat and how fast. a 15' diameter above ground pool is about 4' tall, thats a pretty decent hunk of water to heat without any help. It is also usually coloured sky Blue not a nice dark colour like Black. Personally an above ground pool doesnt really need help getting heated up except in the spring and for that throw a few black rubber mats into the pool and let the sunshine in. An in-ground pool needs more help in the spring and through out the year so a passive solar heater works very well. If your very lazy and like to tinker you can even setup the heater with a small silk stocking filter to heat the water on the winter pool cover and pump it under the cover saving yourself adding more water to the pool after you pumped all the snow melt off the top. If you do this you have the pool opened about 6 weeks before anyone else in the neighbour hood and the pool is comfortable to swim in as well.

The parents place has had this kind of setup since 1985 and it's always the first pool open and the last pool closed. Add to this the automatic pool vaccuum (kreepy crawly) and the only pool maintenance required is adding chemicals. This can also be automated but wheres the fun in that.

WHat is needed at night and on cold days is the insulating blanket. In the day time you need a black floating non insulating covering for when you are not swimming. This will trap heat and reduce evaporative cooling in the daytime.

A solar loop will also help

Hi aurizon,

Sounds like you found a good secondary answer there. Not good enough to work alone but to back up other heat sources it sounds a really good idea.

Take care

reflecting light on another side, to be turned upside down for the (starry) nights, to reduce heat radiation

First thing to do when getting serious on an issue like this is to get an idea of your actuall power needs that have to do mostly with heat losses from pool to ambient depending on temp difference achieved and it's insulation and haven't heard much about it in discussion. Other factors of course contribute to how fast water temp will rise to balance. Power need is possibly easier to measure than to calculate in your case.